Although technology and magic are almost inextricably entwined in the Starfinder Roleplaying Game, magic nonetheless works according to specific rules that have little to do with machinery. This chapter lays out the process of casting a spell, details how to counter and combine magical effects, describes how special abilities work, defines each mechanical element listed in Starfinder's spell descriptions, and includes those spell descriptions.

Casting Spells

When your Starfinder character casts a spell, she is harnessing the latent magical energy that permeates the universe to achieve specific, measured effects. Whether you're playing a mystic or a technomancer, or a character who has gained the ability to manipulate magical energies through some other more unusual means, casting a spell in Starfinder follows one basic process, as described below. A cast spell always has obvious effects that are noticeable by nearby creatures; it is not possible to clandestinely cast a spell. For information about casting a spell as a spell-like ability, see Spell-Like Abilities.

Choosing a Spell

The first step in casting a spell is to choose which spell to cast. Your class's Spells section describes which class's spell list you can choose from, how to determine the number of spells you know, and at which levels you can learn new spells. You also might know spells from a different source, in which case that source provides the details you need to know.

When you cast a spell, you can select any spell you know, provided you are capable of casting spells of that level or higher. Casting a spell counts against your daily limit for spells you cast of that spell level (your “spell slots”), but you can cast the same spell again if you haven't reached your limit. For more information on how to choose which spells your character can access, see your class's information on spells.

Spell Level, Caster Level, and Spell Slots

Once you've chosen a spell to cast, take note of its spell level, and then determine the caster level at which you cast it. A spell's spell level (also referred to as simply “a spell's level”) defines at what class level you can cast the spell. In the case of variable-level spells, the spell's level determines the spell's exact effects (see Variable-Level Spells below). On the other hand, the caster level at which you cast a spell governs many aspects of how the spell works, often including its range and duration. The following sections further describe and differentiate spell level and caster level.

Some of the rules in this chapter make reference to spell slots. The number of spell slots of any given level that you have is equal to the number of spells of that level that you can cast each day (for details about exactly when you regain your daily spell slots, see Regaining Daily-Use Abilities and Spells).

When the rules say you must have an available spell slot, it means that you can't have cast all of your spells per day of that level. When the rules say that you lose a spell slot or the spell fails, that means that you have expended one of the total number of spells of that level that you can cast per day.

Spell Level
A spell level expresses a spell's relative power. A spell's level is listed in its spell description directly to the right of the spell's class icon, and it may vary by class. For example, it is possible for a spell to be a 2nd-level spell for a mystic but a 3rd-level spell for a technomancer. In some cases, a spell's level is listed in its description as “—”. This means you must gain access to the spell through a class feature and can't add it as a spell known through the normal progression of learning spells.

Unlike your caster level, which you can always choose to lower, a spell's level is static unless it is a variable-level spell.

Variable-Level Spells
A variable-level spell is a spell that has different effects depending on the level of the spell slot you use to cast it. The spell description of a variable-level spell lists the spell level as a range (“1-6” for example) and notes how the spell's effects change when cast at different spell levels.

When you learn a spell that can be cast at variable spell levels, you gain the ability to cast it at the spell level you know and at every level below that. For example, let's say Keskodai is a 9th-level mystic who has mystic cure (which is a variable-level spell that can be cast at spell levels ranging from 1st-6th) as a 2nd-level spell known. When Keskodai chooses to cast mystic cure, he can cast it as a 1st-level or 2nd-level spell. His caster level is still 9th, regardless of the spell level at which he casts the spell. Keskodai can't cast mystic cure as a 0-level spell (since mystic cure doesn't have a 0-level version) or as a 3rd-level spell (since he doesn't know mystic cure as a 3rd-level spell). The effect of mystic cure when Keskodai casts it is detailed in the spell's description and depends on the spell level at which he chose to cast it.

If you know a variable-level spell and later select it again as a higher-level spell known, you can immediately select a new spell known to replace the lower-level version of the variable-level spell. For example, when Keskodai becomes a 10th-level mystic, he selects mystic cure as a 4th-level spell known. He also immediately selects a new 2nd-level spell known to replace the 2nd-level version of mystic cure. He can now cast mystic cure as a 1st-, 2nd-, 3rd-, or 4th-level spell.

Caster Level
Your caster level (or CL) represents your aptitude for casting the spells you know, and it is equal to the total number of levels you have in spellcasting classes. For characters with a single spellcasting class, this is equal to your class level in that class. You can cast a spell at a lower caster level than normal, but the caster level you choose must be high enough for you to cast the spell in question, and all level-dependent features must be based on the same caster level. If you wish to cast a spell at a lower caster level than normal, you must decide this before you make any other decisions about the spell's effects. Once a spell has been cast, the spell effect has a caster level that is equal to the caster level at which you cast the spell. Many of a spell's effects are based on the spell's caster level.

In the event that a class feature or special ability provides an adjustment to your caster level, that adjustment applies not only to effects based on caster level (such as range, duration, and damage dealt) but also to any caster level checks you attempt (see below) and DCs based on caster level (such as the DC to dispel your spells).

Caster Level Checks
The rules sometimes require you to make a caster level check. To attempt a caster level check (such as to overcome a creature's spell resistance), roll 1d20 and add your caster level.

Concentration and Interrupted Spells

To successfully cast a spell, you must concentrate. The length of time you must concentrate to cast a spell is specified in the Casting Time entry in the spell's description. Your foes can interrupt your spellcasting in a few ways, as described below.

The concentration required to cast a spell is sufficient to cause you to briefly lower your defenses. If a foe threatens the space you are in, casting a spell provokes an attack of opportunity unless the spell specifies otherwise.

Normally, you can concentrate even in a distracting situation, but if you're casting a spell and you take damage from either a successful attack that targeted your AC or from an effect that you failed a saving throw against, the spell fails. You are most at risk of taking damage while casting when a spell's casting time is 1 round or longer, you have provoked an attack of opportunity, or a foe readied an action to attack you when you began to cast. However, if you are taking ongoing damage (such as if you are bleeding or on fire), your spells are not disrupted in this way.

If you ever try to cast a spell in conditions where the characteristics of the spell can't be made to conform, the spell fails. For example, if you try to cast a spell that targets a humanoid on a non-humanoid, the spell fails.

Concentrating in Harsh Environments

If you attempt to cast a spell in environmental conditions that make spellcasting impossible, the spell fails. You can typically cast spells in bad weather or when your ship is making tricky maneuvers, but at the GM's discretion, if you are subject to extremely violent motion (such as an earthquake) or extremely violent weather (such as a hurricane), you can't concentrate to cast spells. For more information on environments and their rules effects.

The Spell's Result

For details about a spell's range, targets, and other mechanical details, see the spell descriptions, where the details of Starfinder's spells are presented. Once you know which creatures (or objects or areas) are affected, and whether they have succeeded at their saving throws (if any were allowed), you can apply whatever results a spell entails. Spell effects tend to vary by school, which are also described in School and Descriptor.

Many common spell effects are described in Defining Effects.

Attacks
Some spell descriptions refer to attacking. All offensive combat actions, even those that don't damage opponents, are considered attacks. Anytime you would need to make an attack roll to determine whether your spell hits a target, you are considered to be making an attack.

Even an effect that is inoffensive or beneficial to some affected creatures still counts as an attack if it would be considered offensive to any affected creature. Spells that deal damage, spells that opponents can resist with saving throws (and that are not harmless), and spells that otherwise harm or hamper subjects are attacks.

Bringing Back the Dead
Magic and technology can restore slain characters to life. Bringing someone back from the dead involves magically retrieving his soul and returning it to his body.

Negative Levels: Any creature brought back to life by raise dead usually gains 2 permanent negative levels. These levels apply a penalty to most rolls until removed through spells such as restoration.

There is an exception to this rule, though. If the character was 1st or 2nd level (or CR 2 or less for a monster) at the time of death, instead of gaining negative levels, the character's Constitution score is permanently reduced by 2 (or its Constitution modifier is permanently reduced by 1 for a monster).

Preventing Revivification: Enemies can take steps to make it more difficult for a character to be returned from the dead using normal magical means. Keeping the body of a deceased individual, for instance, prevents others from using raise dead to restore the slain character to life. Additionally, finding a way to capture the slain creature's soul prevents any sort of revivification unless the soul is first released, since raise dead and similar magic works by returning the deceased individual's soul to his body.

Revivification Against One's Will: A soul can't be returned to life if it doesn't wish to be. A soul automatically knows the alignment and patron deity (if any) of the character attempting to revive it, which may be a reason it refuses to return.

Combining Magic Effects

Spells or magical effects usually work as their descriptions state, no matter how many other spells or magical effects happen to be operating in the same area or on the same recipient. Except in special cases, a spell does not affect the way another spell operates. Whenever a spell has a specific effect on other spells, the spell description explains that effect. Several other general rules apply when spells or magical effects operate in the same place.

Duplicate Effects

Spells and effects that provide bonuses or penalties to attributes such as attack rolls, damage rolls, and saving throws usually do not stack with themselves if multiple effects would apply to the same attribute. More generally, two bonuses of the same type do not stack even if they come from different spells or from effects other than spells (see Bonuses).

However, damage from multiple spells that deal damage is always cumulative.

Different Strengths

In cases when two or more spells produce identical effects in the same area or on the same target, but at different strengths (such as one spell granting fire resistance 5 and another granting fire resistance 10), only the one with the highest strength applies. If a previously cast spell lasts longer than a more recently cast spell producing the same effect, and the most recent version expires, the previously cast spell resumes its effect for the remainder of its duration.

Multiple Mental Control Effects

Sometimes magical effects that establish mental control render each other irrelevant, such as spells that remove the subject's ability to act. For example, a creature under the effect of a hold person spell cannot be compelled to move using a dominate spell, because the hold person effect prevents the creature from moving.

Mental controls that don't remove the target's ability to act don't usually interfere with each other. If a creature is under the mental control of two or more creatures, it tends to obey each to the best of its ability and to the extent of the control each effect allows. If the controlled creature receives conflicting orders simultaneously, the competing controllers must attempt opposed Charisma checks to determine which one the creature obeys.

Countering and Negating

Some spells can be used to counter other specific spells, as noted in their spell descriptions. For instance, you can use slow to counter a casting of haste. This works exactly like the counter effect of the dispel magic spell, except you don't need to attempt a caster level check; if the target is in range, the spell is automatically countered and fails.

Many times, these same spells note that they negate one another as well. This means that a successful casting of one spell on a target under the effects of the second spell undoes those effects, and the effects of the first spell don't occur.

Special Abilities

A number of classes and creatures gain the use of special abilities, many of which function like spells. A special ability is either a spell-like ability, a supernatural ability, or an extraordinary ability. See Special Abilities for more information.